Collaborative Research: Improved Instrumentation for Arctic Submarine-Based Geophysical Surveys

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This work is to develop an improved geophysical instrument package for use on US Navy nuclear-powered submarines during science cruises to the Arctic Ocean. The authors plan an integrated data acquisition system that would expand the current instrument suite to include a swath-bathymetric imaging system, a "chirp"-type low frequency bottom penetrating sonar and an integrated data logging and quality control computer system. With specifically adapted instrumentation the submarine is the only platform for underway marine geophysical surveys in the high Arctic. The proposed 12 kHz bathymetric imaging system will acquire co-registered bathymetry and backscatter from the seafloor across a swath up to 20 km wide. Data from the "chirp" sonar will, under favorable conditions, define the acoustic stratigraphy of at least the upper 100 m sediment below the seafloor. Transducers for both sonars will be housed in a single, pod secured beneath the submarine. The combined backscatter, bathymetry, "chirp" profiles and gravity anomaly data collected over the entire deep Arctic Ocean will not only provide the basis for solving some of the vexing problems of Arctic tectonics, it will also provide an essential database for planning future coring, dredging or deep sea drilling. This instrument package will make the most of the opportunity generously offered by Navy of operational support for annual submarine cruises through 1999. Critical design goals include: collection of high quality data, dockside installation (i.e. without dry-docking), boat to boat transfer with modest effort and cost; and minimization of returns from the ice canopy. The proposed development, integration and testing effort is a complex undertaking, requiring coordination between participating organizations, user community and the submarine fleet. These submarine cruises will be the only opportunity to systematically collect this data with a set of optimized instruments over the entire ocean basin. The combined suite of swath bathymetry and backscatter imagery, gravity anomaly data, bottom penetrating chirp sonar and possibly magnetometer data will provide a complete geophysical characterization of the morphology, recent sedimentology, shallow stratigraphy and deep structure of the major Arctic Ocean basins. This dataset will revolutionize our understanding of the tectonic history of the Arctic Ocean and the surrounding continents and provide essential information for other disciplines and future scientific exploration of this poorly known region.